Subj : Create Only One Instantance of the Same Application
To   : borland.public.cpp.borlandcpp
From : akuma
Date : Wed Dec 29 2004 05:20 pm

Hi, I have problem on avoiding the same application running many times by 
the CreateEvent / CreateMutex API function after my system was upgraded to 
Windows XP SP2 from SP1.

I tried the following example:

//
BOOL IsAppRunning (LPCTSTR szAppString)
{
    TCHAR    szEventName[MAX_PATH];
    HANDLE g_hAppRunningEvent = INVALID_HANDLE_VALUE;

    lstrcpy (szEventName, TEXT("Global\\SingleInstApp_"));
    lstrcat (szEventName, szAppString);
    g_hAppRunningEvent = CreateEvent (NULL, FALSE, FALSE, szEventName);
    if (g_hAppRunningEvent != NULL) {

        // See if the event already exists.
        if (GetLastError() == ERROR_ALREADY_EXISTS) {
            // The app is already running
            CloseHandle(g_hAppRunningEvent);
            g_hAppRunningEvent = NULL;
        }
    }
    //g_hAppRunningEvent is destroyed when the app terminate
    return (g_hAppRunningEvent == NULL);
}
//

This works only on Windows XP SP1 or before. It does nothing on Windows XP 
SP2. Please help me, thanks!

.